Н. Sxey.—Smokeless and Self-feeding Furnace. 27 
clean and glowing fuel remains, and is by the same means supplied with a 
constant stream of oxygen; heat of any required intensity is thus produced, 
which can be adjusted by regulating the blast. If we take the experimental 
quantity of 1-5 tons of lignite, and consume it in twenty-four hours, then the 
furnace must be supplied with a charge of 14105. of fuel every six minutes, 
and às this fuel yields on analysis 5:5 per cent. of ash, it follows that only 
31b. of ash requires removing and carrying along with the draught in the 
six minutes. 
We may now consider whether tbere is really any loss of power, and, if so, 
how much, by the use of a blast. By its use, the tall chimney is, of course, 
dispensed with. It may be thought that the draught caused by ordinary 
chimneys costs nothing ; but is it not a fact that a certain amount of motive 
force, or its equivalent of heat force, is used in the act of causing a draught in 
common chimneys, and that if all the heat of the furnace were really utilized 
(as by evaporating the theoretical amount of water, for instance), there could 
then be no heat left to expand the column of air in the chimney to work the 
draught, for the gases evolved would be no hotter than the ordinary 
temperature of the atmosphere? The modern theory of heat shows that in 
whatever manner work is done, if work be done at all, then its equivalent of 
heat force is expended. Now, the column of ascending gases and air in a 
chimney is continually pushing away the atmosphere and making room for 
its passage through it. The furnace may be taken as so much colder by 
that amount, that is, there will be that amount of heat less that can be used 
for evaporating the water. 
Experiment No. 1.—In a closed furnace, specially arranged so that no air 
could pass into it except through the burning fuel, a thermometer was attached 
so that the bulb projected into the furnace about 3 in. above the fuel, until it 
showed a constant temperature of 286^, with the damper open; then, on 
shutting the damper in the chimney, in seven minutes it rose to 358^ ; then 
opened it a very little, the temperature at once fell proportionately to the 
amount that the damper was opened ; on opening it wider, it fell to 285^; 
then completely closed it, when it rose in three minutes to 3207. This 
experiment was varied with like results. Also, on another occasion, when the 
thermometer was removed and a vessel of water placed on the top, it 
commenced boiling when the damper was shut, and immediately ceased when 
it was opened. This was repeated several times, which results may be 
ascribed principally to the fact of the gases above the fire being more easily 
heated under the extra pressure when the damper is shut; for when it is 
opened, then some of the heat can exert itself in expanding the gases in the 
chimney, and thus disappears. Now let the chimney be removed and the fire 
supplied with the same amount of air from a blast, and there can be no more 
